lavf/dashdec: add 3GPP TS26.247 probe in dash demuxer

Enabled the 3GP-DASH Release-10/Relase-11(3GPP TS26.247) profile
to dash demuxer probe.

Signed-off-by: Jun Zhao <barryjzhao@tencent.com>

libavformat/dashdec.c

@@ -2361,7 +2361,8 @@ static int dash_probe(const AVProbeData *p)
     if (av_stristr(p->buf, "dash:profile:isoff-on-demand:2011") ||
         av_stristr(p->buf, "dash:profile:isoff-live:2011") ||
         av_stristr(p->buf, "dash:profile:isoff-live:2012") ||
-        av_stristr(p->buf, "dash:profile:isoff-main:2011")) {
+        av_stristr(p->buf, "dash:profile:isoff-main:2011") ||
+        av_stristr(p->buf, "3GPP:PSS:profile:DASH1")) {
         return AVPROBE_SCORE_MAX;
     }
     if (av_stristr(p->buf, "dash:profile")) {